Running Economy Part II – Biomechanical Factors

In a previous article, we presented the topic of running economy (RE) and how important it is for both elite and recreational runners. Running economy is a complex, multifactorial concept that combines metabolic, cardiorespiratory, biomechanical (movement) and neuromuscular characteristics during submaximal effort. By improving your RE, you will be rewarded with more enjoyable running for many years.

Many of the factors of RE can be adjusted with training or other interventions, while some are set in stone. The confusing part, unfortunately, is that what works for one person, may not necessarily work for another. To optimise your running, a clinical running assessment and individualised program will improve your running economy in the fastest way possible.

Biomechanical factors can be further broken down into INTRINSIC and EXTRINSIC variables. Intrinsic variables are comprised of your individual biomechanics, for example stride frequency, stride length, vertical oscillation and ground contact time (GCT). Extrinsic variables focus on footwear, orthoses, and running surface compliance. In this article, we shall take a closer look at some of the modifiable intrinsic variables.

Stride frequency and stride length are generally self-selected. This ‘self-optimisation’ is a physiological adaptation that is dependent on the EXPERIENCE of the runner. Highly trained runners may only need smaller changes of up to 3% (faster or shorter), where-as the recreational runner may need a change of up to 8%.

Vertical oscillation is the up and down movement of your center of mass. Runners that have a lot of vertical oscillation, have reduced RE, AND as runner’s fatigue, vertical oscillation increases! This is generally attributed to the metabolic cost of supporting your body weight for 5, 10, or 100 km. Ensuring that your running technique minimises vertical oscillation and performing appropriate strength and conditioning will help your RE in this aspect.

GCT represents the duration, usually in milli-seconds, that each foot is on the ground. Research on this topic is varied, so it is most likely going to come down to the individual runner’s characteristics and training capacity. Shorter GCT requires trained neuromuscular pathways to handle the explosive and elastic recoil that is associated with fast twitch muscle fiber recruitment, slower GCT requires increased strength because force is produced more slowly. It may be that the most important aspect is not related to the GCT, but the amount of deceleration, or braking force, of the leading leg.

This article has touched on the importance of several key intrinsic variables that can be manipulated to enhance running RE, but it is by no means definitive. Are you looking to get more out of your running? Then improving some, or all, of these variables can help you. In the next article, we shall look at some of the extrinsic variables that can impact RE.